Howell Jenkins, more commonly known as the Wizard Howl, is a character in Howl's Moving Castle, Castle in the Air and House of Many Ways. He is a wizard in the land of Ingary. He also has several other aliases in Ingary: he is known as Wizard Pendragon in posh Kingsbury, and Sorcerer Jenkin in lower-class Porthaven. Howl's country of origin is Wales (presumably the real world version of Wales), which is a world away from Ingary.

Note: Yes, it is 'Jenkin' in Porthaven, not 'Jenkins'. Strange but true.

Howl is vain about his appearance, forever wearing gaudy clothes and spending hours in the bathroom. He dyes his hair different colors, as well - its natural hue is a kind of mud-brown. For much of Howl's Moving Castle he wears a grey and scarlet suit which has a charm on it. (To be fair, it wasn't him who put the charm on it - but then, there's no sign he ever tried to get it removed.) Howl is described as "a slitherer outer", and also a "unprincipled, slippery rogue with a glib tongue and a clever mind", both of which are very true. He is a spendthrift. He can be brave only when pretending he is a coward. He constantly falls in love with young women, but only until they fall in love with him, and then he is bored with them and has nothing to do with them.

Despite all his faults, however, Howl is not as bad as he seems. He undercharges customers who haven't the means to pay for his spells and he took Michael in off the street after Michael's parents died, and has looked after him ever since.

Howl turns 10 000 days old when the Witch's curse catches up with him, making him 27 years old. This also places his birthday (calculating backwards from the average date of midsummer) sometime around January 27th.